Cutting tool holder and a cutting insert therefor

ABSTRACT

Disclosed is a cutting tool holder for mounting a cutting insert having a top face, a bottom face and an insert bore having an inner surface extending between the top and the bottom faces. The holder includes a seat having a bottom surface and at least one side wall angled to the bottom surface, a seat bore with a bore axis having an open end at the bottom surface of the seat, and a securing mechanism for securing the cutting insert in the seat. The securing mechanism includes a securing pin within the seat bore and a body with an outer surface extending between a proximal end and a distal end of the body. The securing mechanism includes a displacement arrangement separate from the securing pin for axially displacing the securing pin along the bore axis of the seat bore between a first, mounting position and a second, securing position.

The present application is for a patent of Addition to our U.S. Pat. No.183,721 filed Jun. 6, 2007, U.S. Pat. No. 184,091 filed Jun. 20, 2007,U.S. Pat. No. 184,742 filed 19 Jul. 2007, U.S. Pat. No. 18,659 filed 10Oct., 2007 and U.S. Pat. No. 190,100 filed Mar. 11, 2008, and disclosesseveral additional variations and improvements in the cutting tool andcutting insert therefor described in those patent applications.

BACKGROUND OF THE INVENTION Field of the Invention

The cutting edges of cutting tools wear rapidly when used for cuttingoperations, particularly when cutting hard materials such as metal, andtherefore they must be frequently replaced or resharpened. In many typesof cutter machines, such as milling machines, the cutting tool includesa plurality of such cutting edges formed in cutting inserts which arefixed within seats in the cutting tool. Each such cutting insert usuallyincludes a plurality of cutting edges, which are sequentially orientedin cutting operations by indexing the cutting insert within therespective seat of the cutting tool.

In the conventional cutting tool, the cutting insert is attached withinthe seat of the cutting tool by a fastener passing through a bore in thecutting insert into the bottom of the seat in the cutting tool. Indexingthe cutting insert to enable the use of another cutting edge requiresthe removal of the fastener, the reorientation of the cutting insert,and the reattachment of the cutting insert within the seat of thecutting tool. Each of these operations involves time and labor, andsince cutting tools generally include a plurality of such cuttinginserts, the time and labor costs involved in indexing the cuttinginserts in a cutting tool are considerable.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a cutting tool, and acutting insert therefor, which enable indexing of the cutting insert tobe effected in a minimum of time and with a minimum of labor. Anotherobject of the invention is to provide a cutting tool, and a cuttinginsert thereof, which do not require the use of a separate fastener tobe inserted and removed in order to permit the mounting of the cuttinginsert onto the cutting, as well as attachment and detachment of thecutting insert during an indexing operation.

According to one aspect of the present invention, there is provided acutting tool holder adapted for mounting thereon a cutting insert havinga top face, a bottom face and formed with an insert bore having an innersurface extending between said top and said bottom face; said holdercomprising a seat defined by a bottom surface and at least one side wallangled to said bottom surface, a seat bore with a bore axis having anopen end at the bottom surface of said seat, and a securing mechanismfor securing said cutting insert in said seat, said securing mechanismcomprising a securing pin received within said seat bore and having abody with an outer surface extending between a proximal end and a distalend of the body and defining a pin axis therealong, and a displacementarrangement adapted for axially displacing said securing pin along thebore axis of said seat bore between at least a first, mounting positionin which said distal end protrudes from within the seat bore throughsaid bottom surface into said seat to a first extent so as to allow saidcutting insert to be placed within the seat, having its bottom facealigned against said bottom surface, and a second, securing position inwhich said distal end protrudes from within the seat bore through saidbottom surface into said seat to a second extent, greater than saidfirst extent, so as to engage the inner surface of said insert bore,thereby securing said insert in place.

It should be understood that the term ‘aligned’ refers to aconfiguration in which said bottom face and said bottom surface aregenerally parallel to one another. It should also be understood thatsaid bottom face and bottom surface do not necessarily have to be incontact with one another, i.e. may be spaced from one another.

In addition, it is to be further understood that the term ‘mountingposition’ is used hereinafter to define a position allowing not onlymounting of the cutting insert onto the holder, but also dismounting ofthe cutting insert therefrom, as well as releasing the cutting insert toa certain extent allowing changing orientation thereof.

According to a specific example of the present invention, thearrangement may be such that in both positions said proximal end may belocated within said seat bore. Alternatively, according to anotherexample, said seat bore may be adapted for receiving an intermediaryarrangement having a bore adapted to receive said securing pin, in whichcase in both positions, said proximal end located within the bore ofsaid intermediary arrangement.

Said cutting insert may be further formed with a side face, wherein whenthe cutting insert is secured within the seat of the cutting toolholder, the securing pin is adapted to apply pressure on the innersurface of said insert bore so as to facilitate firm engagement of saidat least one side face with said at least one side wall of said seat.Said cutting insert may further be formed with another side facecomprising a cutting edge.

The arrangement of said securing pin and the inner surface of saidcutting insert may be such that the pin axis is angled to the innersurface of said cutting insert to thereby apply pressure to said innersurface in the direction of said at least one side wall, i.e. such thata portion of the cutting insert defined between the inner surface andsaid at least one side face facing the side wall of said seat isfastened between the distal end of said securing pin and said side wall.Such an arrangement may be achieved by any of the followingconfigurations:

-   -   the securing pin has a surface portion pin axis is perpendicular        to the bottom surface of said seat and the inner surface of said        cutting insert is angled to bottom face thereof;    -   the pin axis is angled to the bottom surface, i.e. not        perpendicular thereto and the inner surface of said cutting        insert is perpendicular to said bottom face; and    -   both the pin axis and the inner surface are angled, i.e. not        perpendicular, to the bottom surface of the seat and the bottom        face of the cutting insert respectively.

It should also be noted in this connection that the angle between thebottom surface of said seat and said at least one side wall is notlimited to an acute angle and may be a straight angle (90° and may evenbe an obtuse angle.

Said displacement arrangement may be an arrangement separate from thesecuring pin adapted to mechanically engage the securing pin, or theproximal end thereof, such that displacement of the arrangement entailsdisplacement of the securing pin in the axial direction. Examples ofsuch arrangement may be a biasing spring, a bolt or a wedge adapted topress against the securing pin.

In particular, when a biasing spring is used as suggested above, it maybe arranged such that the securing pin is constantly urged by thebiasing spring into said securing position. Thus, switching the securingpin's position to the mounting position may be achieved by simpledepression of the biasing spring.

Specifically, in order to release a cutting insert from the holder,depression of the biasing spring may be achieve by applying pressure onthe securing pin. According to one example, the cutting insert may beformed such that the insert bore is open at both ends, i.e. at the topand bottom face, wherein a pressure instrument may be inserted into thebore through the top face of the insert to apply pressure to the distalend of the securing pin for depression of the biasing spring. Accordingto another example, said securing pin may be formed with a nook and saidholder or said cutting insert is formed with a recess, arranged so as tobe aligned with said nook at said securing position. Thus, a pressureinstrument may be inserted into said recess to be received within saidnook and apply pressure to said securing pin for depression of thebiasing spring.

Alternatively, the securing pin may be integrally formed with thedisplacement arrangement, such that displacement of the pin in a certaindirection entails its axial movement. One example of such an arrangementmay be one in which said securing pin is formed with an external threadreceivable within an inner thread of said seat bore such that rotationof the pin entails progression thereof along the axial direction. Thesecuring pin may be formed at one of its ends with a bolt head adaptedfor receiving a rotary instrument such as a screwdriver adapted forrotation of the securing pin.

In particular, said securing pin may be designed such that the distalend thereof is formed with the bolt head, wherein said rotary instrumentis adapted to engage the securing pin from the top, i.e. such that isfirst passes through said cutting insert to engage the bolt head. Insuch a case, the insert bore may have an opening at both the top andbottom face. Alternatively, said proximal end may be formed with saidbolt head wherein said rotary instrument is adapted to engage thesecuring pin from the bottom, i.e. such that is first passes through theholder to engage the bolt head.

However, as previously defined, in displacement of the securing pinbetween the mounting position and the securing pin, the distal end ofthe securing pin, regardless of its being formed with a bolt head ornot, is displaced farther away from the bottom surface and into theseat.

It should be noted with respect to the above examples, that the timerequired for mounting, dismounting or reversing a cutting insert isgenerally less time consuming than similar operations in conventionalcutting tools (bolting), this being a result, inter alia, of thesimplified method of changing the position of the securing pin (e.g.depression of a spring), and the fact that the securing pin remainswithin the seat bore at all times. This latter feature for example, mayreduce the risk of losing a bolt during such an operation. It shouldalso be noted that the importance of reducing the amount of timerequired for performing the above operation increases in directproportion to the number of cutting inserts used in the cutting tool.

Said tool holder may be formed with two adjacent side walls, and theseat may be adapted is adapted to receive the cutting insert such thattwo adjacent side faces of the cutting insert are aligned with said twoadjacent side walls of the seat. The two adjacent side walls of the seatmay further be formed with a seat securing portion adapted to securelyengage a matching insert securing portion formed in the two adjacentside faces of the cutting insert. The securing portion of said side faceand side wall may be formed as a male/female type connection. Forexample, said side face may be formed with a groove extending along saidside face generally parallel to said bottom surface, and defined by afirst and a second groove surface, angled to one another, and said sidewall may be formed with a corresponding protrusion, similarly extending,and being defined by a first and a second protrusion surfaces,matchingly angled to one another to be received within said groove. Theangle between the groove surfaces may range from 150° to 30°.

In operation, a variety of loads is applied to the cutting insert, interalia, an axial load in a direction generally perpendicular to saidbottom surface which may cause disengagement of the bottom face from thebottom surface. However, the above described engagement between thesecuring portion of the side walls of the seat and the securing portionof the side faces of the cutting insert may be such that the cuttinginsert is adapted to bear against said axial load, so long as the bottomface of the cutting insert is prevented from sliding displacement withrespect to the bottom surface of said seat in a direction facing awayfrom said side walls. In other words, so long as disengagement of thesecuring portion of the side faces from the securing portion of the sidewalls is prevented, the cutting insert may withstand the axial load andprevent disengagement of the bottom face from the bottom surface.

For this purpose, said tool holder may be formed with an arrestingmember and said cutting insert may be formed with an arresting portionadapted to engage said arresting member when mounted onto the seat ofthe tool holder, in a manner preventing said sliding displacement.According to one example of the present invention, said securing pin mayalso constitute the arresting member, wherein the pressure applied tothe inner surface of the cutting insert thereby is such that preventssaid sliding displacement.

In addition, said cutting tool is also adapted to withstand a tangentialload, i.e. a load applied in a direction parallel to the bottom surfaceand bottom face of the tool holder and cutting insert respectively,applying pressure against the side wall of said seat. According to aspecific example, the side wall may be angled to the bottom surface atan acute angle, and said side face may be correspondingly angled to thebottom face at an acute angle. Such an arrangement may provide that thepressure applied to the side face due to the tangential load causes awedge effect entailing downward pressure on the cutting insert firmlypressing the bottom face of the cutting insert to the bottom surface ofthe seat. It should also be noted that the angle is such that the wedgeeffect is sufficient to overcome the static friction generated betweenthe side face and the side wall.

Said cutting tool holder may be used for a variety of cutting operationssuch as milling, drilling, turning etc. and may be adapted to receive aplurality of cutting inserts simultaneously.

According to one specific design embodiment of the present invention,said cutting tool holder may be used for a milling operation, in whichcase said cutting insert is a milling insert. Said tool holder may beadapted for receiving a plurality of milling inserts.

According to another specific design embodiment, said cutting tool is adrilling tool adapted for rotation about a central axis and said cuttinginsert is in the form of a drill head. Said drill head may comprise adrill head body having drilling portion comprising at least one cuttingedge and mounting portion adapted to engage with a securing mechanism,and a positioning element. In addition, said drill head body may beformed with a plurality of body portions, each comprising a drillingportion and a securing mechanism. Accordingly, said tool holder may beformed with a plurality of seat portions adapted for securely receivingtherein the securing mechanisms.

The securing mechanism may be formed with an insert bore adapted toreceive a securing pin of the cutting tool, and a bottom and side facesadapted for alignment against corresponding bottom surface and sidewalls in a manner similar to that previously described. Particularly,the arrangement may be such that the side walls of the tool holder arecounter-disposed, wherein the drill head is securely held in place andprevented from rotating in one direction (e.g. CW) due to the sidewalls, and to the other direction (CCW) due to the securing pin.

Additionally, the bottom surface of the seat of the cutting tool mayhave a conical configuration with respect to the central axis thereof,e.g. having an outer edge and an inner edge, the outer edge beingpositioned axially lower with respect to the inner edge. The bottom faceof the drilling portion of the drill head may have a correspondingopposite configuration, i.e. having an outer edge and an inner edge, theouter edge being positioned axially higher with respect to the inneredge. Such a configuration may facilitate automatic self centralizing ofthe drill head with respect to the tool holder.

Said positioning element may be adapted to be aligned with acorresponding positioning portion of said tool holder. For example, saidpositioning element may be an extension receivable within acorresponding bore of said tool holder. The positioning portions of thedrill head and of the tool holder may be formed with a bayonetarrangement, for further securing the drill head from disengaging fromthe tool holder.

According to another example, the cutting tool is a variable diametercutting tool adapted for rotation about a central axis thereof, and forreceiving at least two cutting inserts circumferentially disposed aboutthe central axis. Said cutting tool may further comprise a diameterregulating arrangement adapted for radially displacing the cuttinginserts with respect to said central axis in order to increase/decreasethe circumference envelope of the cutting tool.

In particular, said diameter regulating arrangement may have a portionthereof constituting the side wall of said seat, outwardly slanted fromthe central axis with respect to the bottom surface. Said side wall maythus extend between a proximal end adjacent said bottom surface andspaced at a radius r₁ from the central axis, and a distal end remotefrom the bottom surface and spaced at a radius r₂>r₁ from the centralaxis. Correspondingly, the cutting insert may be formed with a side faceslanted with respect to the bottom face thereof, and extending between atop end adjacent said top face and a bottom end adjacent said bottomface. The angle between the side face and the bottom face may be suchthat allows aligning the side face of the cutting insert with the sidewall of diameter regulating arrangement.

Said diameter regulating arrangement may be adapted to displace withrespect to said bottom surface, and in particularly, displace such thatthe distal end of said side wall changes its axial position with respectto the bottom surface.

Thus, due to displacement of the diameter regulating arrangement, eachcutting insert may displace between a first, completely overlappingposition, in which the top end thereof is adjacent the distal end ofside wall of the diameter regulating arrangement, and a second,partially overlapping position in which the top end thereof is adjacentthe proximal end of side wall of the diameter regulating arrangement. Itshould also be noted that said cutting insert may assume a variety ofintermediary positions between said completely overlapping and partiallyoverlapping positions.

For example, said varying diameter element may be a screw having aconically shaped head constituting the side wall, wherein screwing andunscrewing of the bolt causes axial displacement of the head thereof andconsequently radial displacement of the cutting inserts, facilitated bya wedge effect.

According to another design embodiment, said cutting insert may have acircular form defining a rotation axis, i.e. a cylindrical side faceextending between the top and bottom face thereof, such that a cuttingedge is defined between the top face and the cylindrical side face. Saidcutting insert may be adapted for rotation about said rotation axisduring a cutting operation.

In operation, when the cutting insert comes in contact with a workpieceto be cut thereby, the loads applied to the cutting insert preventrotation of the cutting insert, in particular due to increased staticfriction forces between the bottom face of the cutting insert and thebottom surface of said seat. However, upon disengagement of the cuttinginsert from the workpiece, i.e. at the instance the cutting insertdisconnects from the workpiece, the load on the cutting insert isdrastically reduced. At that particular instance, there exists a minutetime interval in which the cutting insert, is not longer in contact withthe workpiece compared to the tool holder and the securing pin. At thatparticular time interval, there is a slight reduction in the pressureapplied by the securing pin on the inner surface of the insert bore,allowing the cutting insert to perform a slight rotary motion about itsrotation axis.

The above time interval is extremely short, and allows the cuttinginsert to perform an extremely minute angular rotation about therotation axis. For example, while a cutting too may perform about 3000rounds per minute (RPM), the cutting insert may take up to fifteenminutes to complete a full turn, i.e. performing one turn for every45,000 turns of the cutting tool.

Such an arrangement may provide constant dynamic change of the cuttingedge without the intervention of an operator. Constantly changing thecutting edge may help prolong the effective operation time of thecutting tool.

The circular cutting insert may further be formed with ribs disposed onthe top surface thereof (serving as rake), arranged such that during acutting operation, the cutting insert is urged to rotate in only onedirection.

It should be noted in this respect that the rotation of the circularcutting insert is facilitated by the specific mounting arrangementaccording to the preset invention. In other words, in conventionalmounting using a screw fastener, the cutting insert is much morerestricted in its movement and is less likely to perform a constantdynamic rotation about the axis thereof.

According to another aspect of the present invention there is provided acutting insert configured for used with the cutting tool holder of theprevious aspect of the present invention.

In particular, said cutting insert may be configured to operate inconjunction with the securing mechanism of the cutting tool holder ofthe previous aspect of the present invention.

According to yet another aspect of the present invention there isprovided cutting insert adapted to be mounted onto a seat of a cuttingtool holder having a bottom surface and at least two adjacent side wallsextending therefrom, said cutting insert having a top face and a bottomface defining therebetween a central axis, and at least two adjacentside faces extending between said top face and said bottom face, suchthat when mounted onto said seat said bottom face is aligned with saidbottom surface; each of said two adjacent side faces being formed withan insert locking portion which is adapted, when said cutting insert ismounted onto said seat, to securely engage a corresponding seat lockingportion formed in each of said two adjacent side walls to therebyprevent displacement of said bottom face with respect to said bottomsurface in an axial direction; said cutting insert further being formedwith an arresting portion adapted, when said cutting insert is mountedonto said seat, to engage a corresponding arresting member of saidcutting tool holder, so as to prevent sliding displacement of saidbottom face with respect to said bottom surface, thereby ensuring secureengagement between said insert locking portion and said seat lockingportion.

According to still another aspect of the present invention there isprovided a cutting tool comprising a cutting tool holder and a cuttinginsert according to the previous aspects of the present invention.

According to yet another aspect of the present invention there isprovided a method for mounting a cutting insert according to one aspectof the present invention onto a seat of a cutting tool holder accordingto another aspect of the present invention, said method including:

-   -   displacing a securing pin of said tool holder into a first,        mounting position in which the distal end thereof protrudes from        within the seat bore through said bottom surface into said seat        to a first extent;    -   placing said cutting insert onto said seat such that the bottom        face thereof is aligned with the bottom surface of said seat;        and    -   displacing said securing pin into a second, securing position in        which said distal end protrudes from within the seat bore        through said bottom surface into said seat to a second extent,        greater than said first extent, so as to engage the inner        surface of said insert bore, thereby securing said insert in        place;

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIG. 1 is a schematic cross-sectional view of a typical cutting toolcomprising a cutting tool holder and a cutting insert according to theprior art;

FIG. 2A is a schematic cross-sectional view of a cutting tool comprisinga cutting tool holder and a cutting insert according to one embodimentof the present invention;

FIG. 2B is a schematic cross-sectional view of a cutting tool accordingto another aspect of the present invention;

FIG. 3 is a schematic top view of the cutting tool shown in FIG. 2B;

FIGS. 4A to 4C are schematic cross-sectional views of three stagesinvolved in mounting the cutting insert as shown in FIGS. 2B and 3 intothe seat of the cutting tool holder shown in the same Figs.;

FIG. 5 is a schematic cross-sectional view of one modification of thecutting tool shown in FIGS. 2B and 3;

FIG. 6 is a schematic top view of the cutting tool and cutting insert ofFIG. 5;

FIG. 7 is a schematic cross-sectional view of another modification ofthe cutting tool shown in FIGS. 2B and 3;

FIGS. 8 to 11 are schematic cross-sectional views of the cutting toolaccording to various embodiments of the present invention;

FIG. 12 is a schematic cross-sectional view of the cutting tool inaccordance with another embodiment of the present invention;

FIG. 13 is a schematic top view of the upper surface of the cuttinginsert used in the cutting tool shown in FIG. 12, with the securing pinremoved to show the configuration of the bore therein;

FIG. 14 is a schematic top view similar to that of FIG. 13, showing thesecuring pin;

FIG. 15 is a schematic cross-sectional view of yet another constructionof the cutting tool according to still another embodiment of the presentinvention;

FIG. 16 is a schematic cross-sectional view of a cutting tool accordingto yet a further embodiment of the present invention;

FIGS. 17 to 20 are schematic cross-sectional views of illustrate acutting tool according to still further embodiments of the presentinvention;

FIG. 21 is a schematic cross-sectional view of cutting tool according toanother embodiment of the present invention;

FIGS. 22 to 24 are schematic cross-sectional views of cutting toolsemploying various cutting inserts according to different embodiments ofthe present invention;

FIG. 25 is a schematic cross-sectional view of a cutting tool accordingto still a further embodiment of the present invention employing areversible cutting insert;

FIGS. 26A to 26C are schematic top views of three variations of theembodiment of the cutting tool shown FIG. 25;

FIGS. 27A to 27C are schematic top views of three additional variationsof the above embodiments of the cutting tool according to the presentinvention;

FIG. 28A is a schematic cross-sectional view of a further embodiment ofthe cutting tool, similar to that shown in FIG. 25;

FIGS. 28B to 28D are schematic side, top and perspective views,respectively, of the securing pin used in the cutting tool shown in FIG.28 a;

FIGS. 28E to 28G are schematic top, cross-sectional andbroken-perspective views respectively of the cutting insert shown inFIG. 28 a;

FIGS. 29A to 29C are schematic perspective, side and top views ofanother embodiment of the securing pin used in the cutting tool shown inFIG. 28 a;

FIG. 30A is a schematic cross-sectional view of a cutting tool accordingto yet a further embodiment of the present invention;

FIG. 30B is a schematic top view of the cutting tool shown in FIG. 30 a;

FIG. 30C is a schematic perspective view of the securing pin shown inFIG. 30 a;

FIG. 31A is a schematic exploded perspective view of a cutting toolaccording to a still further embodiment of the present invention;

FIG. 31B is a schematic top plan view of the cutting tool shown in FIG.31 a;

FIG. 31C is a perspective view of a securing pin used in the cuttingtool shown in FIG. 31 a;

FIG. 32A is a schematic exploded perspective view of a still furtherembodiment of the invention;

FIG. 32B is a schematic top plan view of FIG. 32 a;

FIG. 32C is a schematic perspective view of the securing pin used in thecutting tool shown in FIG. 32 a;

FIG. 32D is a schematic cross-sectional view of the cutting insert usedin the cutting tool shown in FIG. 32 a;

FIG. 32E is a schematic cross-sectional view of a spring disc used inthe cutting tool shown in FIG. 32 a;

FIG. 33 is a schematic cross-sectional view of a cutting tool accordingto a further embodiment of the present invention;

FIGS. 34A to 34C are schematic cross-sectional views illustrating threestages of mounting a cutting insert into a seat of a cutting tool holderaccording to another embodiment of the present invention;

FIG. 35 is a schematic cross-sectional view of a cutting tool accordingto still a further embodiment of the present invention;

FIG. 36 is a schematic cross-sectional view illustrating the operationof the cutting tool shown in FIG. 35;

FIG. 37 is a schematic exploded perspective view of a cutting toolholder and a triangular cutting insert according to yet a furtherembodiment of the present invention;

FIG. 38 is a schematic exploded perspective view of cutting tool holderand a rectangular cutting insert according to still a further embodimentof the present invention;

FIG. 39A is a schematic cross-sectional view of the cutting insert shownin FIG. 38;

FIG. 39B is an isometric section view of a cutting tool according to yetanother embodiment of the present invention.

FIG. 40 is a partially exploded perspective view of a milling tool and aplurality of cutting inserts according to another embodiment of thepresent invention;

FIG. 41 is a perspective view of a milling tool comprising a pluralityof circular cutting inserts in accordance with another embodiment of thepresent invention;

FIG. 42 is a partially exploded view of the milling tool shown in FIG.41;

FIG. 43 is an enlarged top view of one of the cutting inserts used inthe milling tool shown in FIGS. 41 and 42;

FIG. 44 is an enlarged perspective section view of the cutting insertshown in FIG. 43;

FIG. 45A is an isometric view of a drilling tool comprising a drillholder and a drill head according to another embodiment of the presentinvention;

FIG. 45B is an isometric view of an enlarged detail A shown in FIG. 45A;

FIG. 45C is an isometric view of detail A shown in FIG. 45B with thedrill head removed;

FIG. 45D is a top view of the drilling tool shown in FIG. 45A;

FIG. 45E is a cross-sectional view of a portion of the drilling tooltaken along line A-A shown in FIG. 45D;

FIG. 45F is a cross-sectional view of a portion of the drilling tooltaken along line B-B shown in FIG. 45D;

FIG. 45G is an enlarged view of a detail B shown in FIG. 45D;

FIGS. 45H to 45L are respective isometric, side, top, front and bottomviews of a drill head used in the drilling tool of FIGS. 45A to 45F;

FIG. 46 is a cross-sectional view of a portion of a drilling toolaccording to another embodiment of the present invention;

FIGS. 47A and 47B are isometric and top views of a variable diametercutting tool according to an embodiment of the present invention;

FIG. 47C is a cross-sectional view taken along line B-B shown in FIG.47B;

FIG. 47D is a cross-sectional view of a portion of the cutting toolshown in FIGS. 47A to 47C, in an additional operational position;

FIGS. 48A and 48B are isometric and top views of the variable diametercutting tool shown in FIGS. 47A to 47D, with the cutting insertsremoved;

FIG. 48C is a cross-sectional view taken along line B-B shown in FIG.48B;

FIGS. 49A and 49B are isometric and top views of a variable diametercutting tool according to another embodiment of the present invention;and

FIG. 49C is a cross-sectional view taken along line A-A shown in FIG.47B.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to FIG. 1, a typical cutting tool according to the priorart is shown comprising a cutting tool holder and cutting insert. It isobserved that the construction therein illustrated includes a cuttingtool holder 2 formed with a seat 3 for receiving the cutting insert 4having a plurality of cutting edges, one of which is shown at 5. Thecutting insert 4 is further formed with a central bore 6 for receiving athreaded fastener 7 having an enlarged conical head 8. The fastener 7 isessentially a bolt inserted into and passed through bore 6 from its topside and threaded into a threaded socket 9 formed in the bottom surfaceof the seat 3.

It is observed that in such a prior art construction, each time thecutting insert 4 is to be mounted, dismounted, reversed or rotated toorient a fresh cutting edge 5 for a cutting operation, it is necessaryto remove the fastener 7, remove the cutting insert 4, rotate it apartial rotation (e.g., 90° in a square cutting insert having fourcutting edges on its top face, and four cutting edges on its bottomface), and reapply fastener 7 through bore 6 into socket 9 of thecutting tool. The term ‘remove’ is referred to herein as defining thatthe fastener 7 is completely disengaged from, and does not contact thetool holder 2. This series of operations requires significant labor andtime for each cutting insert to be indexed, which is multiplied by thenumber of such cutting inserts used in a cutting tool. In addition, oncethe fastener 7 is removed, it may be displaced or lost, which mayfurther consume valuable time.

With reference to FIG. 2A, a cutting tool, generally designated 10 isshown comprising a cutting tool holder 11 and a cutting insert 13securely received therein by a securing mechanism 11′.

The cutting tool holder 11 is formed with a seat 12 defined by a bottomsurface 12 a and a side wall 11 a angled to the bottom surface 12 a atan acute angle. The seat 12 is in turn formed with a seat bore 18defining an axis Y, and adapted to receive therein the securingmechanism 11′.

The securing mechanism 11′ comprises a hollow securing pin 16 and abiasing spring 17 received therein to engaging therewith. The securingpin 16 has an open proximal end pe received within the seat bore 18 anda closed distal end de axially protruding from the bore 18 through thebottom surface 12 a into the seat 12. The arrangement is such that thebiasing spring biases the distal end de of the securing pin 18 toprotrude from the bottom surface 12 a.

The securing pin 18 is further has a securing portion adjacent thedistal end de thereof, having a tapering shape defining a conicalsecuring surface 16 a. The distal end de is also formed with an indent16 b, the purpose of which will be discussed with respect to FIGS. 4A to4C.

The cutting insert 13 has a top and bottom faces 13 a, 13 brespectively, and four side faces 13 c extending therebetween. Thecutting insert 13 is formed with a plurality of cutting edges 14 definedat the intersection between the side faces 13 c and the top and bottomfaces 13 a, 13 b respectively. The cutting insert 13 is further formedwith a conical insert bore 15 adapted for receiving the securing portionof the securing mechanism 11′, and having an inner surface 15 a adaptedto engage the securing portion of the securing mechanism 11′.

In assembly, when the cutting insert 13 is mounted onto the seat 12 ofthe tool holder 11, the bottom face 13 b thereof is flush against thebottom surface 12 a of the seat 12, and a side face 13 c thereof isflush against the side wall 11 a of the seat 12. In this position, theforce of the biasing spring 17 urges the securing pin 16 upwards wherebythe conical surface 16 a of the securing portion 16 engages the conicalsurface 15 a of the insert bore 15. Due to the conical shape of theinsert bore 15 and the conical surface 16 a, the cutting insert 13 ispressed against the side wall 13 to be firmly held in place. It is alsonoted that there exists a gap n between the securing pin 16 and the sideof the inner surface 15 a opposite the side wall 13.

It should also be noted, that while axial displacement of the securingpin 16 upwards entails lateral displacement of the cutting insert 13towards the side wall 11 a, an attempt for displacement of the cuttinginsert 13 in the opposite lateral direction, i.e. away from the sidewall 11 a will not entail downward axial displacement of the securingpin 16 back into the seat bore 18. This is due to the tapering angle ofthe insert bore 15, being close to 0°. In this particular case, theangle β is about 10°. Such an arrangement provides an extremely solidsecuring of the cutting insert 13 within the seat 12.

As seen in particularly in FIG. 2B, a different design of the cuttinginsert 13 is shown in which the side face 13 c is formed with a cut-outdefining an additional surface 13 g angled thereto, and the seat 12 ofthe tool holder is formed with a side wall 11 a having a correspondingshape. In this particular design, the cutting insert 13 is laterallypressed to the side wall 11 a by the securing pin 16 such that thebottom face 13 b is flush against the bottom surface 12 a, while thesurface 13 g is flush against a matching surface 11 g. This, the surface13 c of the side face does not come in contact with the side wall 11 a,and may be used to relief pressure as known per se.

FIGS. 4A to 4C illustrate how such a construction enables the cuttinginsert 13 to be applied to the cutting tool holder 11 and securedtherein without the need for applying and removing separate fasteningelements.

In the initial position shown in FIG. 4A, the securing pin 16 is in asecuring position, its distal end de protruding from the bottom surface12 a to an extent P₁ under the biasing force of the spring 17. Also inthis position, the proximal end pe of the securing pin 16 is locatedwithin the seat bore 18.

In order to mount the cutting insert 13 into the seat 12, the securingpin 16 must first be displaced into a mounting position in which thedistal end de thereof protrude from the bottom surface 12 a to an extentP₂<P₁ allowing the cutting insert 13 to be positioned within the seat 12as previously described. Displacing the securing pin 16 into themounting position required depressing the biasing spring 17 to allow thesecuring pin 16 to axially displace into the seat bore 18. Although suchdepression may be done using an instrument (not shown), it may also beachieved by using the bottom face 13 b of the cutting insert 13 to pressdown on the securing pin 16 as shown in FIG. 4B. Once the securing pin16 is depressed to a sufficient extent, i.e. the distal end de thereofprotrudes to an extend P₂ or less, the cutting insert 13 may be slidinto place.

Once the cutting insert 13 is slid into the seat 12, the securing pin 16is free to displace axially upwards under the force of the biasingspring 17, such that it is received into the insert bore 15. Thesecuring pin 16 displaces upwards until the securing portion 16 athereof engages the inner surface 15 a of the insert bore 15. Uponengagement, the securing pin's 16 upward axial displacement entailslateral displacement of the cutting insert 13 towards the side wall 11 auntil the cutting insert 13 reaches the position shown in FIG. 4C. Inthis position, as previously disclosed, the cutting insert 13 is firmlypressed against the bottom surface 12 a and side wall 11 a of the seat12.

In order to release the cutting insert 13 from the seat 12, it isnecessary to displace the securing pin 16 back to the mounting position,i.e. depressing the securing pin 16 such that the distal end de thereofprotrudes from the bottom surface 12 a to a small enough extent so as toallow the cutting insert 13 to be removed. This may be achieved, forexample, by inserting a tool into the insert bore 15 to engage theV-shaped recess 16 b of the securing pin 16 and applying pressurethereto. Such pressure will cause the securing surface 16 a of thesecuring pin 16 to disengage from the respective surface 15 a of thecutting insert, thereby enabling the cutting insert 13 to be removedfrom the cutting tool holder 11. The actual removal may be done by hand,by a magnet, or by a tweezers—type implement.

With respect to the above, the following should be noted:

-   -   the term ‘mounting position’ should be understood in the        broadest sense and refers to a position allowing mounting and        dismounting of the cutting insert 13, as well as rotation of the        cutting insert 13 for the purpose of switching a cutting edge        14; and    -   In both the mounting position and the securing position, the        proximal end pe of the securing pin 16 is received within the        seat bore 12.

The above disclosed cutting tool 10 and stages of mounting/dismountingoperations of the cutting insert 13 onto the cutting tool holder 11 aresimple, and allow saving a considerable amount of time in performingsuch operations. Furthermore, since the securing pin 16 remains withinthe seat bore 18 at all times, there is less risk of losing ormisplacing it, as may happen with a screw, as known from the prior art.

FIGS. 5 and 6 illustrate a modification wherein the removal of thecutting insert 13, when released by depression of the securing pin 16,is effected by an ejector spring 19 interposed between the cuttinginsert 13 and the bottom of a second bore 19 a formed in the cuttingtool holder 11. As shown in FIG. 6, ejector spring 19 in bore 19 a islocated at the juncture of the two sides of the cutting insert formedwith the shoulders interlocking with corresponding shoulders in thecutting tool holder 11.

FIG. 7 illustrates another embodiment of the cutting tool generallydesignated 21, wherein the cutting insert 23 is formed with cuttingedges 24 and central bore 25, and the securing pin 26 is receivablewithin the bore 25. In this case, only a portion of the distal end de ofthe securing pin 26 is formed with the tapered surface, as shown at 26a, conforming to the taper of bore 25 formed in the cutting insert 23.The remainder of securing pin 26 is of cylinder configuration, as shownat 26 b. The proximal end of the securing pin is formed with an annularstep 26 c, and with an outwardly-extending flange 26 d engageable withan annular shoulder 21 a formed in the cutting tool 21 defining the seat23. FIG. 7 illustrates the operative position of the cutting insert 23,corresponding to that of FIG. 4C.

As further shown in FIG. 7, the bottom of bore 28, housing securing pin26 and its spring 27, is closed by a closure plate 29 secured to thecutting tool 21 by fastener 29 a. Fastener 29 a is provided merely tofacilitate assembly of the cutting tool and its spring-urged securingpin 26 and, of course, need not be removed when removing the cuttinginsert or when indexing it to enable a fresh cutting edge to be used.

In FIG. 7, the angle defined by the bottom face and side wall of thecutting insert 23 is indicated as “α”, and the angle of the innersurface of the cutting insert 23 defining the bore 25 with the bottomsurface of the cutting insert is indicated as “β”. Angle α may be equalto, but is preferably less than angle β. For example, angle α may be75°; angle β may be 82.5°; each of the opposite faces of the cuttinginsert may be 15 mm×15 mm; and the thickness of the cutting insert maybe 7.5 mm.

FIG. 8 illustrates a variation wherein a cutting tool 31 is formed witha seat 32 for receiving cutting insert 33 having a plurality of cuttingedges 34 and formed with a bore 35 receiving a securing pin 36 urged byspring 37 in the outward direction to its securing position. In themodification illustrated in FIG. 8, bore 35 formed in the cutting insert33 is of a tapered configuration, whereas the securing pin 36 is of auniform diameter or cylindrical configuration.

In this case, engagement between the securing pin 16 and the insert bore35 takes place between the top edge of the securing pin 16 and the innersurface of the insert bore 35.

FIG. 9 illustrates a further modification, wherein the bore 45 in thecutting insert 43 is of a cylindrical configuration, whereas the distalof securing pin 46 is of a tapered configuration.

FIG. 10 illustrates a further modification wherein both the bore 55 inthe cutting insert 53 and the distal end de of the securing pin 56 areof a tapered configuration, but the interlocking surfaces between thecutting insert 53 and the cutting tool holder 51 are in the form of arib 51 a formed in the side wall 51′ of the cutting tool holder 51, anda recess 53 a is formed in the cutting insert 53.

FIG. 11 illustrates a further modification wherein the cutting toolholder 61 is formed with a shoulder 61 a adapted for engaging a shoulder63 a formed in the cutting insert 63 in the secured position of thecutting insert. Another modification in FIG. 11 is that, in addition tospring 67 received within bore 68 for urging the securing pin 66 in theoutward direction, there is also provided a second spring 69 within abore 69 a for urging the cutting insert 63 out of the seat in thecutting tool 61 upon the depression of the securing pin 66, similar tothat disclosed in FIG. 5.

Turning now to FIGS. 12 to 16, in the embodiments of the inventiondescribed the securing pin is not spring biased in the outwarddirection, but rather is fixed to the bottom of the seat.

With respect to the embodiment illustrated in FIGS. 12 to 14, it will beseen that the cutting tool 71 is formed with a seat 72 for receiving thecutting insert 73 formed with a plurality of cutting edges 74. Thecutting insert 73 is further formed with a bore 75 therethrough which,as described above with respect to FIG. 1, is normally used forreceiving a fastener (7, FIG. 1) for attaching the cutting insert to thecuter tool. In the previously-described embodiments, bore 75 is used forreceiving a securing pin (e.g., 16, FIG. 2) which is spring-urged in theoutward direction. In the embodiment of FIGS. 12 to 14, however, thesecuring pin, therein designated 76, is fixed to, by being integrallyformed with, the bottom of seat 72 at an oblique angle with respect tothe bottom surface of the seat.

To accommodate the obliqueness of securing pin 76, bore 75 in thecutting insert 73 is formed with extensions or enlargements on the outersurface of the cutting insert. FIGS. 12 to 14 illustrate a constructionwherein the cutting insert may be indexed to four positions to enablefour cutting edges 74 on each of the two sides to be used for cuttingoperations. Thus, as shown in FIG. 13, bore 75 in the cutting insertincludes four such extensions or enlargements, each having an axisdisplaced 90° with respect to the axis of the next extension orenlargement. FIG. 14 illustrates the cutting insert 73 after receivingthe obliquely-extending securing pin 76.

As also seen in FIG. 12, the cutting insert 73 is of a similarconstruction as described above, e.g., with respect to FIG. 2, namely itincludes flat upper and lower faces of square configuration, and fourside walls of rhombic configuration, such as to present four cuttingedges 74 on each side of the insert, or a total of eight cutting edgefor cutting operations.

In FIG. 12, the angle “α” and “β” may be the same as angles α and β,respectively, in FIG. 7. That is, α is preferable equal to or less thanβ. For example, a could be 75°, β could be 82.5°, and the cutting insert73 could be 15 mm×15 mm×7.5 mm.

Turning now to FIG. 15, another embodiment of the cutting too accordingto the present invention is illustrates, generally designated 80. Inthis embodiment, the seat bore receives a securing construction 85comprising a support 86, formed at a distal end thereof with a pin bore89 a adapted to receive the securing pin 89. The securing constructionfurther comprises a fixation element 87 transversally disposed about thesecuring pin 89, and biased by a spring 88.

The entire securing construction is fixed in place by the support 86being fixed to the cutting tool 81 by a threaded fastener 86 a, similarto the construction illustrated in FIG. 7. As clearly seen in FIG. 15,the support 86 is coaxial with bore 85, and both axes are at an obliqueangle to the bottom surface of the seat 82.

The securing pin 89 is formed with a cam surface 89 b engageable with acam surface 87 c of the fixation element 87, and the fixation element isformed with a fixating shoulder 87 b adapted to engage a correspondingshoulder 83 b of the cutting insert. The arrangement is such that, whenthe securing pin 89 is depressed, the two cam surfaces cause thefixation element 87 to be displaced laterally away from the side wall 81a of the seat 82. This lateral displacement allows releasing thesecuring protrusion 89 b from the securing shoulder 83 b of the insert,and thereby to permit to the cutting insert to be withdrawn from theseat 82.

It therefore follows, that when the securing pin 89 is in the securingposition, the distal end de thereof protrudes to a first extent from thepin bore 89 a, and when the securing pin 89 is in a second position, itprotrudes from the pin bore 89 a to a second, lesser extent, allowing acutting insert to be mounted into the tool holder 81.

FIG. 16 illustrates a construction similar to that of FIG. 15, andtherefore to facilitate understanding, the corresponding parts have beenidentified by the same reference numerals. In the constructionillustrated in FIG. 16, the cutting tool is provided with a springejector, in the form of two pins 91, 92, each urged by a spring 93, 94,into engagement with the lower surface of the cutting insert 83, suchthat when the securing pin 89 is depressed to release the cutting insertfor removal from seat 82 of the cutting tool 81, by disengagement offixating shoulder 87 b from shoulder 83 b, the spring ejector forces thecutting insert out of the seat 82 for convenient removal therefrom.

Attention is now drawn to FIGS. 17 to 21 illustrating severalembodiments of the cutting tool according to the present invention inwhich the securing pin is manually movable within the bore of thecutting insert to a securing position or to a mounting position.

Thus, as shown in FIG. 17, the cutting tool 101 is formed with a seat102 for receiving the cutting insert 103 such as to define one or morecutting edges 104 for cutting operations. The cutting insert 103 isformed with a bore 105 which receives a securing pin 106 when thecutting insert is inserted into seat 102.

In the construction illustrated in FIG. 17, the securing pin 106 isformed with a tapered head 106 a at its distal end, and with anexternally-threaded shank 106 b threaded in an internally-threaded bore107 extending through the cutting tool 101. The proximal end of securingpin 106 projecting outwardly of bore 107 carries a knob 109 which may bemanually rotated in either direction. The axis of the securing pin 106is substantially parallel to the axis of bore 105 in the cutting insert103.

It will thus be seen that, when the securing pin 106 is rotated in onedirection by knob 109, it is moved axially upwardly to bring its taperedhead 106 a into firm contact with the inner surface 105 a of the cuttinginsert 103 defining its bore 105, thereby displacing the cutting insertlaterally to firmly secure it within seat 102 of the cutting tool 101.On the other hand, when knob 109 is rotated in the opposite direction,securing pin 106 is moved downwardly within bore 105, thereby causingthe tapered head 106 a of the securing pin to disengage from the innersurface 105 b of the insert 103 defining bore 105, to release thecutting insert for removal, or for mounting a new cutting insert intothe seat.

FIG. 18 illustrates a modification of FIG. 17, wherein the securing pin116 is formed with an enlarged head 116 a at its distal formed with anotch 116 b accessible via the open end of bore 115 by a tool, in orderto rotate the securing pin 116 to its respective securing and mountingpositions.

However it should be noted than in both cases, the in order to securethe cutting insert in place, the distal end of the securing pin shouldbe displaced axially upwards, i.e. away from the bottom surface and intothe seat.

FIG. 19 illustrates another construction, wherein the securing pin 126is not externally threaded, but rather is moved axially within bore 125by a moving pin 127 threaded in bore 128 formed in a wall 129 of cuttingtool 121 defining the seat 122. As shown in FIG. 19, the inner end ofthe moving pin 127 is tapered, as shown at 127 a, and the lower surfaceof securing pin 126 is tapered, as shown at 126 a, such that threadingpin 127 inwardly will raise securing pin 126 to firmly bear against theinner surface of the cutting insert 123, and thereby to secure it inposition, whereas rotating pin 127 in the opposite direction, willrelease the distal of securing pin 126 from its securing position withrespect to the cutting insert 123.

FIG. 20 illustrates a still further construction in which the axis ofthe securing pin 136 is oblique to the axis of bore 135 in the cuttinginsert 133. In this case, the distal 136 a of the securing pin 136 isnot necessarily tapered, or may be tapered for only a short portion,since the rotation of knob 139 will also secure and release the securingpin 136 in the same manner as described above with respect to FIG. 17.

FIG. 21 illustrates a construction similar to that of FIG. 20, exceptthat, instead of moving the securing pin to its securing and releasingpositions by a manual knob, the securing pin, therein designated 146, isspring-urged by spring 147 to its securing position, and is depressibleby a tool engaging the upper surface of the securing pin to thereleasing position.

It will be appreciated that the embodiments of FIGS. 17 to 19 could alsobe modified by including a spring to press the securing pin to itssecuring position, and by engaging its upper surface with a tool formoving the securing pin to its releasing position.

Turning now to FIG. 22, there is illustrates a cutting tool 151 formedwith a seat 152 for receiving a cutting insert 153 having a plurality ofcutting edges 154 and formed with a central bore 155. The cutting tool151 further includes a securing pin 156 located within bore 155 andhaving an axis oblique to that of the axis of the bore and of the seat152. Pin 156 is urged in the direction of the arrow by a spring 157within a bore 158 in the cutting tool, and includes a tapered outersurface 156 a at its distal end engageable with the wall of the bore 155of the cutting insert 153.

It will be seen that bore 155 is tapered in the opposite direction fromthe constructions previously described; that is, it increases indiameter in the outward direction; also that side wall 151 a and bottomwall 151 b of the cutting tool 151, defining the seat 152 for receivingthe cutting insert 153 at the side thereof opposite to the cutting edge154, are perpendicular to each other; that is, α=90°.

It will be further seen that the axis of the securing pin 156 (β) to thebottom wall of seat 152 is at a smaller angle than the angle (γ) of theinner surface of bore 153 to the bottom wall of the seat; also that pin156 is urged by spring 157 outwardly to a securing position with respectto the cutting insert 153, but may be manually depressed outwardly torelease the cutting insert for indexing a fresh cutting edge 154 for acutting operation.

FIG. 23 illustrates a similar construction wherein the cutting tool 161is also formed with a seat 162 for receiving a cutting insert 163 formedwith a cutting edge 164 and a central bore 165 for receiving a securingpin 166 having an upper tapered surface 166 a engageable with the innersurface of cutting insert 163 defining its bore 165. In FIG. 23,however, securing pin 166 is not spring-urged to its securing position,but rather includes threads 166 b and a knob 166 c which is rotatable inone direction to secure the cutting insert within seat 162, or in theopposite direction to release the cutting insert for removal from thatseat.

Another difference in the construction of FIG. 23 is that the side wall161 a and bottom wall 161 b, defining the seat 162 opposite to thecutting edge 164, is at an obtuse angle; that is, angle α is greaterthan 90°. However, the cutting insert still remains securely positionedin the mounting position since the inclination angle δ of the axis ofthe securing pin 166 is greater than α.

With reference to FIG. 24, there is illustrated a construction alsosimilar to that of FIG. 22, with the difference being that the side wall171 a and bottom wall 171 b of cutting tool 171, defining the seat 172for receiving the cutting insert 173, is at an acute angle to eachother; that is angle α is less than 90°.

Turning now to FIG. 25 a further construction of the cutting tool isshown wherein the cutting tool holder 181 is formed with a seat 182 forreceiving the cutting insert 183 having a cutting edge 184 and a centralbore 185. In this case, however, the cutting insert 183 is reversible,and the bore 185 is formed with two tapered sections from its midportion 185 a. Thus, one section 185 b tapers from the mid section 185 aoutwardly to one face (the inner face) of the cutting insert, whereasthe other section 185 c tapers from mid portion 185 a outwardly in thedirection of its opposite face (the outer face) of the cutting insert.

Securing pin 186 in FIG. 25 has a longitudinal axis parallel to thelongitudinal axis of bore 185 and includes an upper tapered surface 186a which is urged by spring 187 in bore 188 into contact with the innersurface of bore 185.

It will thus be seen that the construction illustrated in FIG. 25enables the cutting insert 183 to be inserted into seat 182 with eitherface of the cutting insert facing the bottom of the seat 182, therebyenabling all the cutting edges 184 on each of the two opposite faces ofthe cutting insert to be oriented for use during a cutting operation.For example, if cutting insert 183 includes four edges 184 on each face,this arrangement enables eight cutting edges to be used for cuttingoperations.

FIG. 26A is a top view of the construction illustrated in FIG. 25,wherein side wall 181 a and bottom wall 181 b of the cutting toolholder, defining the seat 182 for receiving the cutting insert 183, areat an acute angle to each other on two contiguous sides, therebydefining two projections 189 a, 189 b for securing the cutting insert183 within seat 182 of the cutting tool. FIG. 26B illustrates avariation wherein the two walls 181 a and 181 b of the cutter definingseat 182 are at an acute angle at only one side of the cutting insert,thereby defining a single projection 189 a in the securing position ofthe cutting insert. FIG. 26C illustrates a variation wherein the twowalls 181 a and 181 b are perpendicular to each other such that noprojection is formed in the securing position of the cutting insert, butthe cutting insert is secured in position within the cutting tool by thelateral force applied by pin 186 to the cutting insert.

In most of the above-described embodiments, the securing pin is ofcircular cross-section. FIGS. 27A to 27C illustrate several furthervariations that may be made.

FIG. 27A illustrates a cutting insert 193 receiving a securing pin 196of oblong cross-section; FIG. 27B illustrates a cutting insert 203 forreceiving a securing pin 206 of square cross-section; and FIG. 27Cillustrates a cutting insert 213 for receiving two securing pins 216 a,216 b.

FIGS. 28A to 28G illustrate a cutting tool similar to that of FIGS. 25and 26A to 26C, but including a bore 225 in the cutting insert 223, anda securing pin 226 of a polygonal figuration, more particularly of arectangular configuration (FIG. 28C), rather than the cylindricalconfiguration of bore 185 and securing pin 186 in the construction ofFIGS. 25 and 26A to 26C.

Thus, as shown in FIG. 28A, the cutting tool holder 221 is formed with aseat 222 for receiving the cutting insert 223 of a square configurationas cutting insert 183 in FIGS. 25 and 26A to 26C. Cutting insert 223 isalso formed with a plurality of cutting edges 224, and a central bore225 of a polygonal configuration, in this case of a square configuration(FIG. 28C), rather than of a circular configuration as indicated above.

Thus, as shown more particularly in FIGS. 28E to 28G, cutting insert 223is formed with a square bore defined by four flat sides 223 a-223 d.Cutting insert 223 defining square bore 225 is further formed with foursmall-diameter circular bores 223 c-223 h, one at each of the juncturesof two of its flat sides. The smaller bores 223 c-223 h facilitate themanufacture of the square bore 225, and also distribute and relieve thestresses at the junctures of the flat sides.

In addition, and as shown in FIG. 28A, bore 225 is further formed withtwo tapered sections from its mid portion 225 a, as in FIG. 25, whereinone portion 225 b tapers from the mid portion 225 a outwardly to oneface (the inner face) of the cutting insert, and the other section 225 ctapers from mid portion 225 a outwardly in the direction of its oppositeface (the outer face) of the cutting insert.

Securing pin 226 has a longitudinal axis parallel to the longitudinalaxis of bore 225, and includes an upper tapered surface 226 a (on one ofits flat sides, which side is urged by spring 227 in bore 228 intocontact with the inner surface of bore 225 in the cutting insert 221.

It will thus be seen that the construction illustrated in FIGS. 28A to28G similarly enables the cutting insert 223 to be inserted into seat222 with either face of the cutting insert facing the bottom of the seat222, thereby enabling all the cutting edges 224 on each of the twoopposite faces of the cutting insert to be oriented for use during acutting operation. Whereas, in FIGS. 25 and 26A to 26C bore 185 incutting insert 183, and the upper part of the securing pin cooperablewith the sides of the bore, are both of a circular configuration, in theconstruction illustrated in FIGS. 28A to 28G both are of a polygonalconfiguration, more particularly a square configuration. It will also beobserved as clearly seen in FIGS. 28A to 28D that the flat side 226 a ofsecuring pin 226 cooperable with the cutting insert 223 is of a taperedconfiguration, decreasing in length towards its outer face, whereas theremaining three sides 226 b-226 d are of a non-tapered configuration.

With reference to FIGS. 29A to 29C there is illustrated a securing pin226 of a construction similar to that of the securing pin of FIGS. 28Ato 28G, and therefore to facilitate understanding, corresponding partshave been identified by the same reference numerals. The main differencein the construction of FIGS. 29A to 29C is that the tapered face at thedistal end of the securing pin 226 is rounded, as shown at 226 a′(FIG.29A), rather than flat. Such a construction thus provides line contactbetween tapered side 226 a′ of the securing pin with the correspondingsurface of the cutting insert, rather than surface contact, therebyreducing friction.

FIGS. 30A to 30C illustrate a further construction of the cutting tool231 according to the present invention formed with a seat 232 forreceiving the cutting insert 233 having cutting edges 234 and a centralbore 235 receiving a securing pin 236. As in the previous constructions,the distal 236 a of securing pin 234 cooperates with the cutting insert233, whereas the proximal end 236 b of the securing pin includes aspring 237 which urges the distal end into securing position withrespect to the cutting insert.

In this case, however, the inner portion 236 b of securing pin 236received within bore 238 is eccentric with respect to the upper portion236 a of the securing pin cooperable with cutting insert 233. Inaddition, the inner end 236 b of securing pin 236 terminates in a disc236 c, seatable against the bottom of the seat 238 and of the samediameter as the seat. Further, securing pin 236 also includes anintermediate cylindrical section 236 d coaxial with the inner section236 b and the bottom disc 236 c, and therefore also eccentric withrespect to the upper portion 236 a of the securing pin. The intermediateportion 236 d cooperates with the distal end of bore 238 and is of thesame diameter as that bore.

Spring 237 is a coiled spring enclosing the inner section 236 b ofsecuring pin 236. One end 237 a of the coil spring is fixed to the innerportion 236 b of the securing pin 236, and the opposite end 237 b isadapted to be received within an opening (not shown) in the cutting tool23 a adjacent to its bore 238.

It will thus be seen that securing pin 236 is rotatable within bore 235of insert 233 and bore 238 underlying the seat 232 receiving the cuttinginsert. It will also be noticed that the bottom disc 236 c andintermediate portion 236 d serve as bearing elements eccentric withrespect to the upper portion 236 a of securing pin 236, such thatrotation of the securing pin in one direction by spring 237 causes theupper portion 236 a of securing pin 236 to firmly bear against the innersurface of the bore of the cutting insert 233 to secure the cuttinginsert firmly within the cutting tool 231 for a cutting operation. Itwill also be observed that securing pin 236 may be manually rotated inthe opposite direction (against the force of spring 237) by a wrenchinserted within wrench opening 236 e to move the upper portion 236 a ofthe securing pin to a mounting position with respect to the cuttinginsert, whenever it is desired to re-index the cutting insert fororienting a new cutting edge for a cutting operation.

FIGS. 31A to 31C illustrate a still further embodiment of the invention,wherein the cutting tool holder 241 is formed with a seat 242 forreceiving the cutting insert 243 having a plurality of cutting edges244. Cutting insert 243 is formed with a bore 245 receiving a securingpin 246, such as to firmly secure the cutting insert 243 to cutting toolholder 241 for orienting a selected cutting edge 244 for a cuttingoperation.

As shown particularly in FIG. 31C, securing pin 246 includes an outerend 246 a engageable with the sides of bore 245 in the cutting insert243, and an inner end 246 b which is externally threaded and receivablewithin an internally threaded bore 248 underlying seat 242 in thecutting tool.

The construction illustrated in FIGS. 31A to 31C is thus of somewhatsimilar construction to that of the prior art illustrated in FIG. 1,with the following important differences: In the prior art construction,the bore (6) in the cutting insert (4) is of the same diameter as thethreaded fastener 7, and the head 8 of the threaded fastener is coaxialwith the shank of the threaded fastener 7, and with the threaded bore 9receiving the fastener. In the novel construction, however, asillustrated in FIGS. 31A-31C, the bore 245 within the cutting insert 243is of larger diameter than the upper portion 246 a of the securing pin246, and the upper portion 246 a of the securing pin is eccentric withrespect to the threaded portion 246 of the securing pin. The latter ismore particularly illustrated in FIGS. 31B and 31C, wherein the axis ofthe lower threaded portion 246 b of the securing pin is indicated by a₁,and the axis of the upper portion 246 of the securing is indicated byaxis a₂.

Thus, it should be understood that whereas in the conventionalconstruction the rotation of the fastening member into the cutting toolholder entails application of downward pressure to the cutting insert inthe direction of the bottom surface of the seat, in the presentconstruction, rotation of the securing pin 246 entails lateral pressurein the direction of the side wall of the cutting tool holder 241.

It will thus be noted that, whereas in the prior art of FIG. 1, thefastening pin must be removed in order to index the cutting insert for anew cutting edge, and then reinserted to refasten the cutting insert, inthe construction illustrated in FIGS. 31A-31C, the securing pin 246 neednot be removed from the cutting tool 241 in order to re-index thecutting insert 243. Rather, it needs only to be rotated (e.g., one-halfturn) in one direction to move the cutting insert 243 into a securingposition with respect to the cutting tool 241, or in the oppositedirection to move the cutting insert 243 to a releasing position withrespect to the cutting tool 241 in order to reorient another cuttingedge 244 for a cutting operation. The illustrated construction thusalso, as in previously-described constructions, permits the cuttinginsert 243 to be released for manual indexing another cutting edge,without the need to remove the securing pin and to reinsert it, asrequired in the prior art construction illustrated in FIG. 1.

The construction illustrated in FIGS. 32A to 32E is similar to that ofFIGS. 31A to 31C, except that it includes a conical disc 259 (FIGS. 32Aand 32C) interposed between the outer end 256 a of the securing pin 256and seat 252 of the cutting tool 251. Conical disc 259 is formed with anopening 259 a to receive securing pin 256, and is compressed when thethreaded end 256 b of the securing pin is firmly threaded in threadedbore 258 of the cutting tool 251 to apply an outward pressure to thesecuring pin 256 received within bore 254 of the cutting insert 253.Such a construction thereby provides added protection again theinadvertent rotation of the securing pin 256 from its securing positionwith respect to cutting insert 253 to its releasing position. Thus, theconstruction illustrated in FIGS. 32A to 32D first requires that thesecuring pin 256 be pressed inwardly, and then rotated, in order torelease the pin from its securing position to its releasing positionwith respect to cutting insert 253.

Another difference in the construction illustrated in FIGS. 32A to 32Eis that the upper portion 256 a of securing pin 256 is of cylindricalconfiguration, as clearly shown in FIG. 32C, whereas the upper portion246 a of the securing pin 246 is of conical configuration, as seenparticularly in FIG. 31C.

In all other respects, the construction, operation and advantagesprovided by the cutting tool illustrated in FIGS. 32A to 32E arebasically the same as described above with respect to FIGS. 31A to 31C.

Turning now to FIGS. 33 to 39, there is illustrated a cutting toolsimilar to the construction illustrated in FIG. 25, but modified topermit more firmly wedging the cutting insert between the securing pinand the cutting tool after the cutting insert has been indexed, orreplaced, to provide a new cutting edge for a cutting operation.

Thus, the cutting tool holder illustrated in FIG. 33, and thereingenerally designated 261, is formed with a seat 262 for receiving thecutting insert 263 having a cutting edge 264 and a central bore 265. Asin FIG. 25, bore 265 is formed with two tapered sections from itsmid-portion 265 a, one portion 265 b tapering outwardly to the innerface of the cutting insert, and the other portion 265 c taperingoutwardly to the outer face of the cutting insert.

Securing pin 266 in FIG. 33 has a longitudinal axis parallel to thelongitudinal axis of bore 265, and includes an upper tapered surface to266 a which is urged, by spring 267 in bore 268, into contact with thelower inner surface 265 b of bore 265.

In the construction illustrated in FIG. 33, however, the bottom wall 261a of the bore in cutting tool 261 is formed with a central openingadapted to receive a stem 266 c integrally formed in the securing pin266. It will be seen that spring 267 urges securing pin 266 outwardly.Preferably, stem 266 c is of a length so as to be substantially flushwith the inner surface of cutting insert 261, or slightly recessedtherefrom as shown in FIG. 33.

The purpose of stem 266 c of securing pin 266 is to permit a sharpimpact to be applied to the securing pin in the outward direction, tothereby firmly wedge cutting insert 263 between the securing pin and thecutting tool 261. Preferably, the impact is applied via an impact pin267 having a tip 267 a at one end impactable against the outer tip 266 bof stem 266 c, and thereby to wedge cutting insert 263 firmly withinseat 262 between securing pin 266 and the cutting tool holder 261. Forthis purpose, the outer tip 226 b of stem 266 c is formed with adepression, such as a V-shaped notch, and the corresponding end of 267 aof impact pin 267 is complementarily formed to seat within depression226 b. Impact pin 267 includes, at its opposite end, an enlarged head267 b for receiving an impact by a hammer 269 or other impact-producingmember.

It will thus be seen that after the cutting insert 263 has been indexed,or replaced, to provide a new cutting edge 264 for cutting purposes,spring 267 will normally urge coupling pin 266 outwardly, to therebyfirmly bear against the cutting insert 263, as described aboveparticularly with respect to FIG. 25. However, when the constructionillustrated in FIG. 33 is used, impact pin 267 may be impacted forapplying a sharp impact to securing pin 266 in the outward direction, tomore firmly wedge the cutting insert 263 within seat 262 of the cuttingtool 261.

The cutting tool holder illustrated in FIG. 33 provides all theadvantages described above with respect to the earlier constructions,with the additional advantage of better assuring that the cutting insertwill be firmly wedged in the cutting tool. When only the spring 267 isused to firmly hold the cutting insert 263 within the cutting tool, aload applied by the workpiece against cutting insert 264 may set thecutting tool holder 261 in rapid vibration. Such vibrations tend toloosen the cutting insert 263 from the cutting tool holder 261 in thecourse of time, and to increase the rate of “metal fatigue” undergone bythe cutting tool, thereby substantially decreasing its useful life.However, when the cutting insert is firmly wedged against the cuttingtool holder, by applying an impact to it as described above with respectto FIG. 33, loosening of the cutting insert, and the onset of metalfatigue, are both substantially reduced, thereby producing bettercutting operations and a longer useful life of the cutting insert.

FIGS. 34A to 34C illustrate another cutting tool similar to that of FIG.33, but constructed to firmly wedge the cutting insert between thecutting tool and the securing pin by a simple manual operation, ratherthan by a tool-applied impact operation as in FIG. 33. For the sake ofbrevity the parts in FIGS. 34A to 34C which generally correspond to theparts in FIG. 33 are identified by the same reference numerals.

In the construction illustrated in FIGS. 34A to 34C, the tapered surface266 a of the securing pin 266, and of the engaged surface 265 b of thebore 265 in the cutting insert 263, are configured such as to firmlywedge the cutting insert between the securing pin and the tool holderwhen the cutting insert is applied as shown according to the sequence ofsteps illustrated in 34 a-34 c, respectively. Thus, as shown in FIG.34A, the cutting insert 263 is placed over the securing pin 266 so as toengage the upper surface of securing pin 266 by a portion of the bottomsurface of cutting insert 263 (FIG. 34A); then the cutting insert 263 ispressed downwardly to depress securing pin 266 (FIG. 34B); and finallythe cutting insert 263 is slid laterally across the top of the securingpin until the securing pin pops outwardly within bore 265 of the cuttinginsert (FIG. 34C). Tapered surface 266 a of the securing pin, engagingtapered surface 265 a of the bore 265 within the cutting insert 263,firmly wedges the cutting insert between the securing pin and the sidewall of seat 262 of the cutting tool holder 261. For purposes ofexample, such tapered surface may be about 5-15° preferably about 10°.

All the foregoing operations can be done manually in one continuousmovement, therefore obviating the need for impact elements, such as 267,269 in FIG. 33. To free the cutting insert, an impact tool, such as usedin producing dimples in the surface of a metal workpiece, may be used byapplying the tip of the tool to the upper surface of securing pin 266and impacting it downwardly, thereby moving tapered surface 266 adownwardly with respect to tapered surface 265 b, to release the cuttinginsert for rotation, replacement, etc. when it is desired to provide afresh cutting edge for a cutting operation.

FIG. 35 illustrates another construction, also similar to that of FIGS.33 and 34A to 34C, and therefore for purposes of brevity, the samereference numerals are used to identify corresponding parts. Theconstruction illustrated in FIG. 35 differs from the precedingconstructions in that the side wall 262 a of the seat 262 formed in thecutting tool holder 261 is of a convex configuration, and the outersurface 263 a of the cutting insert 263 is of complementary concaveconfiguration. Such a construction not only produces an interlockformation between the cutting insert and the tool holder, as in thepreviously described embodiments, but also facilitates the handling ofthe shavings by the cutting insert due to the concave rake surface.Thus, as shown in FIG. 36, during a cutting operation with respect to aworkpiece 270, convex surface 263 a of the cutting insert 263 iseffective to deflect the shavings 271 produced by the cutting edge 264outwardly of the cutting insert thereby decreasing the possibility thatsuch shavings will interfere with the cutting operation.

As indicated earlier, the cutting insert may be of any polygonalconfiguration, such as triangular, quadrilateral, hexagonal, octagonal,etc. FIG. 37 illustrates an example wherein the cutting tool 361 isprovided with a triangularly-shaped seat 362, and a cutting insert 363is of similarly triangular shape. The cutting insert includes threecutting edges 364 which may be selectively indexed for a cuttingoperation. Cutting insert 363 is also formed with a bore 365 adapted forreceiving therein a securing pin 366, which may be of any of theabove-described constructions to lock the cutting insert in positionduring the cutting operation, and release it for removal or rotation inorder to present a new cutting edge for a cutting operation.

In addition, each side face 367 is formed with a securing portion in theform of a v-shaped groove 368, adapted to engage a corresponding tov-shaped rib formed in the side wall of the cutting tool holder 361. Thepurpose of the v-shaped groove will no be further discussed with respectto FIG. 38.

FIG. 38 illustrates a construction similar to that of FIG. 10, includinga cutting tool 371 formed with a square seat 372 receives a cuttinginsert 373 of square configuration, including four cutting edges 374 onits upper side, as well as an additional four cutting edges on its lowerside. The cutting insert is further formed with a central bore 375adapted to receive a pin 376 centrally of the seat 372 of the cuttingtool. As in the FIG. 10 construction, the construction illustrated inFIG. 38 also includes a rib 371 a in the two side walls defining theseat 372, and the four outer sides of the cutting insert 373 includefour grooves 373 a for receiving the ribs 371 a when the cutting insertis firmly secured within the seat 372 by securing pin 376.

As distinguished from the FIG. 10 construction, however, the two sides371 b of the cutting tool seat 372 receiving the cutting insert 373extend perpendicularly to the bottom wall of the seat, rather than at anangle thereto as illustrated in FIG. 10. Similarly, the four outer sides373 e of the cutting insert 373 are similarly formed perpendicularly tothe bottom wall of the cutting insert. In all other respects, theconstruction illustrated in FIG. 38, and the operation of such aconstruction, are substantially the same as described above with respectto FIG. 10.

It should be noted here that the interlocking engagement between thev-shaped grooves 373 a and the v-shaped ribs 371 a, provides the cuttinginsert with resistance to axial loads applied thereto during a cuttingoperation, so as to prevent disengagement of the bottom face of thecutting insert from the bottom surface of the seat 372. It should alsobe noted that this resistance to axial loads is provided so long as thecutting insert is prevented from lateral sliding displacement betweenthe bottom face thereof and the bottom surface of the seat, in otherwords, so long as it is secured such that the side face thereof isaligned with the side wall of the seat, and the v-shaped grooves 373 ainterlock with the v-shaped rib 371 a.

In the present example, the securing pin 376 also constitutes anarresting member preventing disengagement of the groove 373 a from therib 371 a. However, it should be understood that the cutting tool holdermay be formed with an arresting member preventing such disengagement.

Turning now to FIGS. 39A and 39B, there is illustrated a cutting tooland cutting insert also similar to that of FIG. 10, but obviating theneed for producing a tapered bore, which is difficult to produce usingstandard manufacturing procedures. To facilitate understanding FIG. 39A,corresponding parts in that figure are identified by reference numeralscorresponding to those used in FIG. 10, but increased by “500”.

Thus, the bore 555 formed centrally in insert 553 is of a cylindrical,non-tapered configuration, rather than of a tapered configuration asillustrated (at 55) in FIG. 10. In addition, rib 551 a in the cuttingtool 551, and the complementary groove 553 a in the cutting insert 553,are of a triangular configuration, rather than of a trapezoidalconfiguration in FIG. 10, and are formed via two respective walls ofcutting tool 551 and cutting insert 553 extending perpendicularly to thebottom wall of seat 552 in the cutting tool.

As further seen in FIG. 39A, bore 558 formed in the bottom wall of seat552 for securing pin 556 and biasing spring 557 is at an oblique angleto the bottom wall of seat 552, rather than perpendicularly thereto asin FIG. 10.

The cutting insert illustrated in FIG. 39A is attachable and detachablewith respect to the cutting tool 551 in the same manner as describedabove with respect to FIGS. 34A to 34 c, and provides the sameadvantages of firmly wedging the cutting insert 553 in seat 552 of thecutting tool 551 in a simple manual operation as described in FIGS. 34Ato 34C. The FIG. 39A construction, however, has the significantadvantage over that of FIG. 10, and that of FIGS. 34A to 34C, in thatthe bore 55, and interengageable walls of cutting tool 551 and cuttinginsert 553, respectively, obviate the need and expense of forming thesewalls in a tapered configuration.

With reference now made to FIG. 39B, an additional modification to thecutting tool of the present invention is shown in which in order todepress the securing pin 566, it is not required to apply pressure fromto the distal end de thereof. In particular, the cutting tool holder 561is formed with a side bore 562 adapted to receive an end 574 of a lever570, to be received within a corresponding recess 569 formed in thesecuring pin 566 adjacent the proximal end pe thereof.

The end portion of the lever 370 is formed with an eccentric protrusion576, wherein, when the protrusion 576 is received within the recess 569,rotation of the lever 370 entails axial displacement of the securing pin566.

FIG. 40 illustrates a cutter head, generally designated 380, formed withfour rectangular seats 382 for releasably receiving four cutting inserts383, each of the construction illustrated in FIG. 38. Thus, as shown inFIG. 39, each cutting insert 383 is formed with four cutting edges 384on each side, and with a bore 385 in its center for receiving a securingpin 386 spring-urged outwardly by a coil spring 387 located centrally ofeach seat 382 of the cutter head 380. In the construction illustrationin FIG. 39A, the corner at two contiguous sides of the seat is formedwith a rounded cut-out 388, similar to the construction illustrated inFIG. 28E, in order to relieve stresses.

It will be appreciated that the constructions illustrated in FIGS. 38,39A and 39B may include a rib 381 b only on one side wall of seat 382,rather than on each of the two contiguous side walls as illustrated inthese figures.

Turning now to FIGS. 41 to 44, in all the above-described constructions,the cutting inserts are of polygonal configuration, with a cutting edgeon each of its sides. FIGS. 41 to 44 illustrate a construction includinga cutter head 460 designed to carry cutting inserts 453 of circularconfiguration, rather than of polygonal configuration, to provide, ineffect, an infinite number of sides of the cutting edge. Theconstruction illustrated in FIGS. 41 to 44 is also such that the cuttinginsert 453 rotates slowly and automatically during a cutting operation,so that it is not necessary to be continuously re-index the cuttinginsert with respect to the cutting edge oriented for the cuttingoperation.

Thus, as seen particularly in FIG. 41, each cutting insert 453 is ofcircular configuration and is received within a seat 451 of acomplementary circular configuration. Each cutting insert 453 is formedwith a continuous circular cutting edge 454 around its outer periphery,and with a central bore 455 for receiving a securing pin 456spring-urged by spring 457 in the outward direction with respect to bore455.

As seen particularly in FIG. 44, the outer surface of each cuttinginsert 453 thus defines a cylindrical side wall, which is formed with atapered recess or groove 453 a around its circumference between the twoend walls of the insert. As shown in FIG. 42, the side wall of thecutter head defining each of its seats 451 for receiving a cuttinginsert 453 is formed with a circular rib 451 a of complementary taperedconfiguration to be received within each of the recessed grooves 453 aof the cutting insert.

As also seen particularly in FIG. 44, the outer surface of each cuttinginsert 453 is formed with a plurality of ribs 458 engageable with theshavings (e.g., 271, FIG. 36) cut from the workpiece during a cuttingoperation by the cutting edge 454 of the cutting insert, to deflect theshavings outwardly of the cutting insert. Ribs 458 are formed obliquelyto the radial lines of the circular cutting insert. This enables theseribs to perform another function, namely to produce a slow rotation ofthe cutting insert during a cutting operation. Thus, the oblique ribs458 continuously change the cutting edge engageable with the workpieceduring a cutting operation.

Tapered surface 456 a of the securing pin 456, and the correspondingsurface of bore 455 formed in the cutting insert 453, would be designedto only lightly secure the cutting insert between the cutting tool andthe securing pin, and to thereby permit the slow rotation of the cuttinginsert during a cutting operation by the engagement of the shavings withthe oblique ribs 458.

In addition, it should be noted that during the cutting operation, whenthe cutting edge of the cutting insert 453 is within the workpiece, theloads and pressure on the cutting insert 453 are such that cause a highstatic friction, preventing the cutting insert 453 from rotating aboutits axis. However, at the instance of disengagement of the cuttinginsert from the workpiece, the pressure is relieved for a briefinterval, in which the cutting insert 453 may perform rotary motion. Therotary motion performed by the cutting insert 453 is minute, forexample, for a milling head rotating at a speed of 3000 RPM about thecentral axis thereof, the cutting insert may perform 1 turn every 15minutes, i.e. 1 turn every 45,000 turns of the milling head.

A construction, such as that illustrated in FIGS. 41 to 44 thus producesa continuous change in the cutting edge during a cutting operation,thereby not only obviating the need to re-index the cutting edge of thecutting insert between cutting operations, but also preventing undueheating of the cutting edge, which is continuously changing, therebysubstantially increasing the useful life of the cutting insert.

Turning now to FIGS. 45A to 45G, a drilling tool generally designated600 is shown comprising a drill body 610 and a drill head 620 mountedthereon. The drill body 610 is formed at one end thereof with a holderportion 611 adapted for receiving the drill head 620 in a secure manner.

The holder portion 611 is formed with a bottom surface 616B, and twoshoulders 614 a, 614 b axially extending from the bottom surface 616Band located at two diametrically opposed location with respect to thecentral axis X. Each shoulder 614 is formed with a side wall 616S whichis angled to the bottom surface 616B, similar to the majority ofembodiments previously disclosed.

The holder portion 611 is further formed with a positioning bore 618 thecenter of which coincides with the central axis, and has an open end atthe bottom surface 616B. The holder portion 611 is also formed with twoseat bores 636 (shown FIG. 45F), each being adapted to receive asecuring mechanism 630 therein.

The securing mechanism 630 comprises a securing pin 632 and a biasingspring 634, similar to the disclosed in several of the previousembodiments.

Referring to FIGS. 45H to 45L, the drill head adapted to be mounted intothe seat of the holder portion 611 is formed with a right side 620R anda left side 620L which are diametrically opposed to one another, eachside being formed with a drilling portion 620D, and a mounting portion620M. Each drilling portion 620D comprises a cutting edge 621. Eachmounting portion 620M is formed with a tapering insert bore 626 and aside face 627. In addition, the drilling head 620 is formed with acentral positioning stub 628, adapted to be received within thepositioning bore 618.

Reverting to FIGS. 45A to 45G, it is observed that when the drillinghead 620 is mounted onto the holder portion 611, the securing pin 632bears against the inner surface 626 i of the insert bore 626, in amanner similar to that described with respect to previous embodiments.However, in the present embodiment, since the diametrically opposedportions 620L, 620R of the drilling head 620 are secured against theshoulders 614L, 614R, the pressure of the securing pins 632 is appliedin opposite direction, or alternatively, in a direction tangent to a CWdirection. This proves an advantage when drilling is concerned since thedrilling tool 600 may be rotated in a CCW direction, thereby onlytightening the engagement between the securing mechanism 630 and thedrilling head 620.

In assembly, the drilling head 620 is placed onto the seat of the holderportion 611 such that the positioning stub 628 is located above thepositioning bore 618, and the bottom face of each of the portions of thedrilling head 620 rests on a respective securing pin 632. From thisposition, the drilling head may be pressed downwards to apply pressureto the securing pins 632, thereby depressing them into a mountingposition, in which the distal end thereof protrudes from the bottomsurface 616B to an extent allowing insertion of the drilling head 620into the seat. Once in the mounting position, the drilling head 620 maybe rotated so as to bring the respective left and right side faces 627to engage the side walls 616S, thereby securing the drilling head inplace.

With particular reference to FIG. 46, a similar embodiment of thedrilling head is shown, however, in this embodiment, the bottom surface616W is of conical shape tapering downwards, thereby facilitating easyand accurate centralization of the drilling had within the holderportion 611.

Turning now to FIGS. 47A to 48C, another embodiment of the presentinvention is shown depicting a variable diameter cutting tool generallydesignated 700, and comprising a holder body 710, three cutting inserts720 mounted thereon using a plurality of securing mechanism 730, and adiameter regulating arrangement 740.

Each cutting insert 720 is mounted onto the holder body 710 in a mannersimilar to that disclosed with respect to previous embodiments, with thedifference being that the holder body 710 is not formed with asupporting side wall against which the securing pin 732 may applypressure. Instead, the holder body 710 is formed with a central bore 746adapted to receive therein a regulator member 742 the head of which isof conical shape, constituting the side wall to define, together withthe bottom surface 716B the insert seat.

With particular attention being drawn to FIG. 47C, the securing pin 732engages the inner surface 726 i of the insert bore 726 to secure thecutting insert 720 between the distal end de of the securing pin 732 andthe head of the regulator member 742 being used as a side wall. In theposition shown in FIG. 47C, the regulator member extends to a distanceh1 above the bottom surface 716B, and the cutting tool has an operativediameter of D1.

The regulator member 742 is received within the bore 746 using a thread,allowing the regulator member 742 to be displaced axially along thebore, and being positioned at a variety of desired distances above thebottom surface 716B. It is also evident that due to the engagementbetween the head of the regulator member 742 and the side face 726S, thelower the extension of the regulator member 742 above the bottom surface716B, the farther the inserts 720 are from each other, and greater theoperative diameter of the cutting tool 700. The regulator member 742 mayalso be indexed as shown by 747 in order to indicate the desiredincrease in diameter.

However, as previously explained with respect to FIG. 2A, whereasdisplacement of the securing pin entails lateral displacement of thecutting insert towards the side wall of the seat, the opposite does nottake place (axial displacement of the securing pin as a result oflateral displacement of the cutting insert). Therefore, axiallydisplacing the regulator member 742 will not entail lateral displacementof the cutting inserts and increase in diameter.

Thus, in operation, when desiring to increase the operative diameter,either of the following may take place:

-   -   a. in case no cutting inserts 720 are mounted onto the cutting        tool holder 710 as shown in FIGS. 48A to 48C, the regulator        member 742 may be freely axially displaced to a desired amount,        and only then are the cutting inserts 720 mounted onto the tool        holder 710 in a manner similar to that described with respect to        previous embodiments; or    -   b. in case cutting inserts 720 are mounted onto the tool holder        710, the securing pin 732 must first be depressed so as to        provide the cutting inserts 720 with a certain degree of freedom        in the lateral direction, and only them may the regulator member        be axially displaced. Once displaced, the securing pins 732 may        be un-depressed and assume a securing position to securely        fasten the cutting inserts 720 in place.

Depression of the securing pins 732 may be achieved using a triple-pinmember (not shown) adapted to be inserted into the insert bores 726 fromthe top side thereof and apply pressure to the securing pins 732.

Turning now to FIGS. 49A to 49C, an embodiment of a cutting too similarto that shown in FIGS. 47A to 48C, is shown generally designated 800,with the difference being it comprising only two cutting inserts 820. Inall other ways, operation is the same as in FIGS. 47A to 48C.

Those skilled in the art to which this invention pertains will readilyappreciate that numerous changes, variations, and modification can bemade without departing from the scope of the invention, mutatismutandis.

1-50. (canceled)
 51. A cutting tool holder adapted for mounting thereona cutting insert having a top face, a bottom face and formed with aninsert bore having an inner surface extending between the top and thebottom faces; the holder comprising a seat comprising a bottom surfaceand at least one side wall angled with respect to the bottom surface, aseat bore with a bore axis having an open end at the bottom surface ofthe seat, and a securing mechanism for securing the cutting insert inthe seat, the securing mechanism comprising a securing pin receivedwithin the seat bore and a body with an outer surface extending betweena proximal end and a distal end of the body and defining a pin axistherealong, and a displacement arrangement separate from the securingpin, the displacement arrangement adapted to mechanically engage thesecuring pin, such that displacement of the arrangement displaces thesecuring pin along the bore axis of the seat bore between at least afirst, mounting, position in which the distal end protrudes from withinthe seat bore through the bottom surface into the seat to a first extentto allow the cutting insert to be placed within the seat, having itsbottom face aligned against the bottom surface, and a second, securing,position in which the distal end protrudes from within the seat borethrough the bottom surface into the seat to a second extent, greaterthan the first extent, so as to engage the inner surface of the insertbore, thereby securing the insert in place.
 52. The cutting tool holderaccording to claim 51, wherein the seat bore is non-threaded.
 53. Thecutting tool holder according to claim 51, wherein the cutting toolholder is formed with a plurality of insert seats configured forsimultaneous engagement with the same cutting insert.
 54. The cuttingtool holder according to claim 51, wherein in both the mounting positionand the securing position, the securing pin remains in engagement withthe tool holder.
 55. The cutting tool holder according to claim 51,wherein in both the mounting position and the securing position, theproximal end is located within the seat bore.
 56. The cutting toolholder according to claim 51, wherein the displacement arrangement is abiasing spring for constantly urging the securing pin into said securingposition.
 57. The cutting tool holder according to claim 51, wherein thecutting tool holder is configured for a variable diameter cutting tooladapted for rotation about a central axis thereof, and is furtherconfigured for receiving at least two cutting inserts circumferentiallydisposed about the central axis, the cutting tool holder furthercomprising a diameter regulating arrangement configured for radiallydisplacing the cutting inserts with respect to the central axis in orderto increase/decrease the circumference envelope of the cutting tool. 58.A cutting tool comprising a cutting tool holder and a cutting insertmounted therein, the cutting insert comprising a top face, a bottom faceand an insert bore having an inner surface extending between the top andthe bottom faces; the holder comprising a seat comprising a bottomsurface and at least one side wall angled with respect to the bottomsurface, a seat bore with a bore axis having an open end at the bottomsurface of the seat, and a securing mechanism for securing the cuttinginsert in the seat, the securing mechanism comprising a securing pinreceived within the seat bore and having a body with an outer surfaceextending between a proximal end and a distal end of the body anddefining a pin axis therealong, and a displacement arrangement separatefrom the securing pin adapted to mechanically engage the securing pin,such that displacement of the arrangement displaces the securing pinalong the bore axis of the seat bore between at least a first, mounting,position in which the distal end protrudes from within the seat borethrough the bottom surface into the seat to a first extent to allow thecutting insert to be placed within the seat, having its bottom facealigned against the bottom surface, and a second, securing, position inwhich the distal end protrudes from within the seat bore through thebottom surface into the seat to a second extent, greater than the firstextent, to engage the inner surface of the insert bore, thereby securingthe insert in place.
 59. The cutting tool according to claim 58, whereinthe seat bore is non-threaded.
 60. The cutting tool according to claim58, the cutting tool holder further comprising a plurality of seatsconfigured for simultaneous engagement with the same cutting insert. 61.The cutting tool according to claim 58, the cutting insert furthercomprising at least one side face, and when the cutting insert issecured within the seat of the cutting tool holder, the securing pinapplies pressure on the inner surface of the insert bore to facilitatefirm engagement of the at least one side face with the at least one sidewall of said seat.
 62. The cutting tool according to claim 58, whereinthe insert seat further comprises two adjacent side walls and isconfigured for receiving the cutting insert such that two adjacent sidefaces of the cutting insert are aligned with the two adjacent side wallsof the seat, at least one of the two adjacent side walls of the seatfurther comprising a seat securing portion for securely engaging amatching insert securing portion formed in a corresponding side face ofthe cutting insert.
 63. The cutting tool according to claim 58, whereinthe arrangement is such that the cutting insert is adapted to bearagainst an axial load attempting to disengage the bottom face from thebottom surface, when the bottom face of the cutting insert is preventedfrom sliding displacement with respect to the bottom surface of the seatin a direction facing away from the side walls.
 64. The cutting toolaccording to claim 58, wherein the cutting tool is configured for anoperation selected from the group consisting of: milling, drilling, andturning.
 65. The cutting tool according to claim 58, wherein the cuttingtool holder is a drilling tool holder and the cutting insert comprises adrill head.
 66. The cutting tool according to claim 65, wherein saiddrill head comprises a plurality of body portions, each having adrilling portion comprising at least one cutting edge and a mountingportion for engaging a securing mechanism.
 67. The cutting toolaccording to claim 65, wherein the side walls of the tool holder arecounter-disposed, such that the drill head is securely held in place andprevented from rotating with respect to the tool holder in one directiondue to the side walls, and in the other direction due to the securingpin.
 68. The cutting tool according to claim 58, wherein the cuttinginsert further comprises a cylindrical side face extending between thetop and bottom faces thereof, and is configured for rotation about arotation axis during a cutting operation.
 69. A method for mounting ontoa seat of a cutting tool holder according to claim 51, a cutting inserthaving a top face, a bottom face and formed with an insert bore havingan inner surface extending between the top and the bottom faces themethod comprising: i. displacing a securing pin of the tool holder intoa first, mounting position in which the distal end thereof protrudesfrom within the seat bore of the cutting tool holder through the bottomsurface into the seat to a first extent; ii. placing the cutting insertonto the seat such that the bottom face thereof is aligned with thebottom surface of the seat; and iii. moving the cutting insert to allowthe securing pin to be displaced by the displacement arrangementcomprised in the cutting tool holder into a second, securing position inwhich the distal end protrudes from within the seat bore through thebottom surface into the bore of the cutting insert to a second extent,greater than the first extent, to engage the inner surface of the insertbore, thereby securing the insert in place.
 70. The method according toclaim 69, wherein step (i) is performed using the bottom face of thecutting insert.
 71. The method according to claim 69, wherein moving thecutting insert is performed by rotating the cutting insert about an axisof the cutting tool holder.
 72. A cutting insert configured for mountingonto the cutting tool holder of claim
 51. 73. The cutting insertaccording to claim 72, wherein the cutting insert comprises a drillhead.
 74. The cutting insert according to claim 73, wherein the drillhead comprises a plurality of body portions, each having a drillingportion formed with at least one cutting edge, and a mounting portionfor engaging with the securing mechanism of the cutting tool holder. 75.The cutting insert according to claim 74, wherein each mounting portionhas a top face, a bottom face and an insert bore having an inner surfaceextending between the top and the bottom faces, the insert bore beingconfigured for engagingly receiving therein the securing pin of thecutting tool holder.
 76. The cutting insert according to claim 75,wherein the insert bore is non-threaded.